keyword = frozen or zero
frozen value = no or yes
no = initialize extended variables using values drawn from equilibrium distribution at Tstart
- yes = initialize extended variables to zero (i.e., from equilibrium distribution at zero temperature)
-
- zero value = no or yes
+ yes = initialize extended variables to zero (i.e., from equilibrium distribution at zero temperature)
+ zero value = no or yes
no = do not set total random force to zero
yes = set total random force to zero
@@ -58,6 +58,13 @@ Fluctuation-Dissipation Theorem. The functional form of the memory
kernel associated with the temporally non-local force is constrained
to be a Prony series.
+IMPORTANT NOTE: While this fix bears many similarities to fix +langevin, it has one significant +difference. Namely, fix gld performs time integration, +whereas fix langevin does NOT. To this end, the +specification of another fix to perform time integration, such as fix +nve, is NOT necessary. +
With this fix active, the force on the jth atom is given as
@@ -89,13 +96,6 @@ the Newtonian and Langevin limits. Details of these limits, and the
associated numerical concerns are discussed in
(Baczewski).
-While this fix bears many similarities to fix -langevin, it has one significant -difference. Namely, fix gld performs time integration, -whereas fix langevin does NOT. To this end, the -specification of another fix to perform time integration, such as fix -nve, is NOT necessary. -
The desired temperature at each timestep is ramped from Tstart to Tstop over the course of the next run.
@@ -126,6 +126,8 @@ to zero by subtracting off an equal part of it from each atom in the group. As a result, the center-of-mass of a system with zero initial momentum will not drift over time. ++
Restart, run start/stop, minimize info:
The instantaneous values of the extended variables are written to @@ -135,6 +137,10 @@ do "exact" restarts with this fix, where the simulation continues on the same as if no restart had taken place. However, in a statistical sense, a restarted simulation should produce the same behavior.
+None of the fix_modify options are relevant to this +fix. No global or per-atom quantities are stored by this fix for +access by various output commands. +
This fix can ramp its target temperature over multiple runs, using the start and stop keywords of the run command. See the run command for details of how to do this. @@ -143,6 +149,10 @@ sense, a restarted simulation should produce the same behavior.
Restrictions: none
+This fix is part of the MISC package. It is only enabled if LAMMPS +was built with that package. See the Making +LAMMPS section for more info. +
Related commands:
fix langevin, fix viscous, diff --git a/doc/fix_gld.txt b/doc/fix_gld.txt index 965652a6c4..295f64e6fb 100644 --- a/doc/fix_gld.txt +++ b/doc/fix_gld.txt @@ -15,7 +15,7 @@ fix ID group-ID gld Tstart Tstop N_k seed series c_1 tau_1 ... c_N_k tau_N_k key ID, group-ID are documented in "fix"_fix.html command :ulb,l gld = style name of this fix command :l Tstart,Tstop = desired temperature at start/end of run (temperature units) :l -N_k = number of terms in the Prony series representation of the memory kernel +N_k = number of terms in the Prony series representation of the memory kernel :l seed = random number seed to use for white noise (positive integer) :l series = {pprony} is presently the only available option :l c_k = the weight of the kth term in the Prony series (mass per time units) :l @@ -24,7 +24,7 @@ zero or more keyword/value pairs may be appended :l keyword = {frozen} or {zero} {frozen} value = {no} or {yes} {no} = initialize extended variables using values drawn from equilibrium distribution at Tstart - {yes} = initialize extended variables to zero (i.e., from equilibrium distribution at zero temperature) :pre + {yes} = initialize extended variables to zero (i.e., from equilibrium distribution at zero temperature) {zero} value = {no} or {yes} {no} = do not set total random force to zero {yes} = set total random force to zero :pre @@ -45,6 +45,13 @@ Fluctuation-Dissipation Theorem. The functional form of the memory kernel associated with the temporally non-local force is constrained to be a Prony series. +IMPORTANT NOTE: While this fix bears many similarities to "fix +langevin"_fix_langevin.html, it has one significant +difference. Namely, "fix gld"_fix_gld.html performs time integration, +whereas "fix langevin"_fix_langevin.html does NOT. To this end, the +specification of another fix to perform time integration, such as "fix +nve"_fix_nve.html, is NOT necessary. + With this fix active, the force on the {j}th atom is given as :c,image(Eqs/fix_gld1.jpg) @@ -76,13 +83,6 @@ the Newtonian and Langevin limits. Details of these limits, and the associated numerical concerns are discussed in "(Baczewski)"_#Baczewski. -While this fix bears many similarities to "fix -langevin"_fix_langevin.html, it has one significant -difference. Namely, "fix gld"_fix_gld.html performs time integration, -whereas "fix langevin"_fix_langevin.html does NOT. To this end, the -specification of another fix to perform time integration, such as "fix -nve"_fix_nve.html, is NOT necessary. - The desired temperature at each timestep is ramped from {Tstart} to {Tstop} over the course of the next run. @@ -113,6 +113,8 @@ to zero by subtracting off an equal part of it from each atom in the group. As a result, the center-of-mass of a system with zero initial momentum will not drift over time. +:line + [Restart, run start/stop, minimize info:] The instantaneous values of the extended variables are written to @@ -122,6 +124,10 @@ do "exact" restarts with this fix, where the simulation continues on the same as if no restart had taken place. However, in a statistical sense, a restarted simulation should produce the same behavior. +None of the "fix_modify"_fix_modify.html options are relevant to this +fix. No global or per-atom quantities are stored by this fix for +access by various "output commands"_Section_howto.html#howto_15. + This fix can ramp its target temperature over multiple runs, using the {start} and {stop} keywords of the "run"_run.html command. See the "run"_run.html command for details of how to do this. @@ -130,6 +136,10 @@ This fix is not invoked during "energy minimization"_minimize.html. [Restrictions:] none +This fix is part of the MISC package. It is only enabled if LAMMPS +was built with that package. See the "Making +LAMMPS"_Section_start.html#start_3 section for more info. + [Related commands:] "fix langevin"_fix_langevin.html, "fix viscous"_fix_viscous.html,